Washington -LRB- CNN -RRB- -- The North Korean government informed the State Department on Friday that it is holding a second American citizen who the North Koreans say entered the country from China , a State Department spokesman said .

The American , who has not been identified , was detained Monday for trespassing on North Korea 's border with China , state-run Korea Central News Agency reported Thursday . The incident is under investigation , according to the agency 's report .

Spokesman P.J. Crowley had said Thursday afternoon that the department had been unable to get information on the reported incident .

North Korea announced December 29 that it was holding an American who had entered the country illegally from China on Christmas Eve . The news agency did not identify the man , who it said was `` now under investigation by a relevant organ . ''

At the time , State Department spokesman Ian Kelly said Washington was concerned by reports that a Korean-American missionary , Robert Park , had gone into North Korea , but could not confirm them .

Washington and Pyongyang have no diplomatic relations . The United States relies on the Swedish Embassy to look after U.S. interests in North Korea .

Crowley has said the United States continues to seek consular access to Park .

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North Koreans say U.S. citizen entered the country from China

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North Koreans also still holding American they say entered illegally on Christmas Eve

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Neither person has been identified ; U.S. worried about missionary Robert Park